Key to the identification and ecology of Daphnia (Crustacea: Cladocera) of North America (north of Mexico)

By Leszek Bledzki

The key to North American (north of Mexico) Daphnia (Crustacea, Cladocera), along with the information about species ecology, distribution and recent taxonomic progress of the field, constructed in such a way that should be easy to use by unexperienced person.

• Language: English
• Publisher: Lulu.com
• Release date: Jan 4, 2023
• ISBN: 9781387303502

Book preview

Preface

Daphnia has been at the forefront of developments in our understanding of the organization of planktonic communities, but it belongs to one of the most difficult (and confused) Cladocera genera to identify. There is an urgent need for the global Daphnia genus revision, which requires all nominative species to be redescribed. The Holarctic Daphnia species and their distribution were recently revived by several authors, but the North American species are still lacking an updated reference, suitable for the identification purposes, this includes many confusions and inappropriate species descriptions, which violated the International Zoological Nomenclature (the review of these was provided in the chapter 13.2 in the Daphnia monograph provided by Benzie (2005) and more recently it was also addressed by Zuykova et al (2018, 2019b). Here provided is a pictorial key to North American Daphnia (north of Mexico), along with the information about species ecology, distribution and recent taxonomic progress of the field, however, this will not fix the above mention problems. The key is constructed in such a way that should be easy to use by unexperienced person. I would like to encourage users of this key to share their constructive ideas, published papers and information that may lead to improvements of the key or better knowledge of species morphology, ecology and distribution. The literature related to zooplankton and Daphnia from North America is very large, scatters in many journals (some hardly accessible) and probably not all distributing records are shown there. Many Cladocera species records are awaiting for the discovery as many lakes, ponds and other water bodies are insufficiently or never have been explored.

Acknowledgments

Author is grateful to many colleagues who provided their published papers over the years, some of them hardly accessible. I would especially thank Gunnar Halvorsen who generously granted me his book (Sars, 1993), Adam Petrusek for his comments on European Daphnia and Jens Petter Nilssen for sharing his comments about Daphnia from his book (An account of the Crustacea of Norway: Cladocera – Norvegiæ, Crustacea; Arthropoda, and challenges in taxonomy and nomenclature of the cladoceran genera Daphnia and Bosmina) before its publication. Both, the Mount Holyoke College Library and Five College Library – Five College Depository staff helped with great resources over many years. I would like to thank my wife, Maria for her long-term support and tolerance for my time spent working on this book.

December 2022, South Hadley/Chicopee, MA & Seattle/Lynnwood, WA, USA            Leszek A. Błędzki

Abbreviations

Cu – Copper

DIC – Dissolved Inorganic Carbon

DOC – Dissolved Organic Carbon

DW – Dry Weight

DVM – Diel Vertical Migration

PAR – Photosynthetically Active Radiation 

UV – Ultraviolet

UVR – Ultraviolet Radiation

Introduction

Daphnia has been for over 240 years at the forefront of developments in our understanding of the organization of planktonic communities (Dodson 1981; Edmondson 1987; Peters and de Bernardi 1987; Gillooly and Dodson 2000; Adamowicz et al. 2004; Benzie 2005; Mergeay et al. 2008; Kotov 2015; Zuykova et al. 2018; Zuykova et al. 2019b). Why Daphnia and how has this approach arisen was already answered long time ago (de Bernardi and Peters 1987; Edmondson 1987). Systematics of Daphnia was shifted back and forth for much over the century (Hrbāček 1987a; Hrbāček 1987b), even with the use of molecular phylogeny (Lehman et al. 1995; Colbourne and Hebert 1996; Adamowicz et al. 2009), but the problem is still not resolved (Benzie 2005; Petrusek et al. 2011; Kotov 2015; Zuykova et al. 2019b), and it will need a huge collaborative effort to accomplish this task, which must include a redescription of all 361 nominative Daphnia species (Kotov 2015). Genus Daphnia contains more than 80 valid species with multiple undiscovered cryptic species able to hybridize, the process which may lay behind the speciation driver (Chin and Cristescu 2021). Resolving the Daphnia taxonomy is not an easy task as Daphnia have a very high degree of genetic variation within a single population of any species (with about 31,000 genes, that is about 1/3rd more than humans), and they are able to change their size and shape responding to the change of environmental conditions (Liu et al. 2019). The progress of Daphnia taxonomy has recently been accelerated, because Daphnia has been a model species in ecology, toxicology, evolution and environmental genomics projects (Lampert 2011; Orsini et al. 2011; Miner et al. 2012; Norambuena et al. 2019; Ebert 2022). However, Kotov (2015) calls for the redescription of all previously described Daphnia taxa, which should be based on anatomical details of males and thoracic limbs of both males and females. The above agree with problems described previously by Benzie (2005) in a chapter 13.2 in his Daphnia monograph.

The progress in Daphnia taxonomy has been provided by many researchers (among others by: Brooks 1957; Schwenk et al. 2000; Billiones et al. 2004; Benzie 2005; Petrusek et al. 2005; Colbourne et al. 2006; Ishida et al. 2006; Petrusek 2007; Petrusek et al. 2008; Adamowicz et al. 2009; Petrusek et al. 2011; Kotov 2013; Popova and Kotov 2013; Kotov 2015; Cornetti et al. 2019; Zuykova 2019; Zuykova et al. 2019b). Adamowicz et al. (2009) described the phylogenetic appraisal of 92 Daphnia species from seven continents. Kotov et al. (2013) provided the world checklist of all Daphnia species. Ebert (2022) described history of the Daphnia major research questions related to genome and phylogenetic position, life cycle, adaptation and resurrection ecology, interaction with parasites, phenotypic plasticity, ecotoxicology, field collection and culture including hutching.

Daphnia have the highest number of published papers among the Cladocera genera, which exceeded approximately 18,392 (Web of Science on December 23, 2022), accounting for about 3/4th of the published papers related to Cladocera. In spite of that, daphniids phylogenetic relationships and taxonomy still remain controversial (Billiones et al. 2004; Kotov 2015). Daphnia belong to one of the most confused and difficult Cladocera genera to identify and have been considered one of the taxonomically most difficult groups of the animal kingdom (Flößner and Kraus 1986; Dlouha et al. 2010).

The genus Daphnia is divided into three subgenera Ctenodaphnia (occurs mainly in the southern hemisphere), Daphnia s. str. (occurs mainly in the northern hemisphere), each containing many species and Australodaphnia with a single species D. occidentalis from Australia, please note that the existence of subgenus Hyalodaphnia is unjustified (Margaritora 1985; Fernando et al. 1987; Hrbāček 1987b; Glagolev 1995; Benzie 2005; Colbourne et al. 2006; Ishida et al. 2006; Popova and Kotov 2013). Using molecular methods Kotov and Taylor (2011) showed that the split of the Daphnia subgenera dates back to the Mesozoic. For many years, authors indicated that molecular data indicates three clear Daphnia groups (Hyalodaphnia, Ctenodaphnia and Daphnia s. str.), each heaving a long history, which may be recognized as subgenera (Colbourne and Hebert 1996; Schwenk et al. 2000; Billiones et al. 2004; Schwenk et al. 2004). Each subgenus has also been divided into a number of species complexes (Colbourne and Hebert 1996). While the taxonomy of Ctenodaphnia is considered well-resolved, species boundaries in the subgenera Daphnia and Hyalodaphnia are uncertain and unjustified, as the morphological characters that separate them are not clear (Benzie 2005; Ishida et al. 2006). In addition, in many cases species-specific characters are dimmed by interspecific hybridization (Schwenk et al. 2000), further complicating the Daphnia taxonomy and identification. Genetic studies have established that hybridization is common between both, closely allied and distant Daphnia species (Colbourne and Hebert 1996). In addition, it was found that two groups (Hyalodaphnia and Daphnia s. str.) are sister groups (Schwenk et al. 2000). Hyalodaphnia and the molecular systematic of this group was examined by several authors (Schwenk et al. 2000; Billiones et al. 2004; Schwenk et al. 2004). They found that species of Hyalodaphnia represent a taxonomically problematic group due to their phenotypic plasticity, local races, and the formation of interspecific hybrids and backcrosses. Recently, many researches divide Daphnia into three groups (Ctenodaphnia, Daphnia s. str. and Australodaphnia), where the Daphnia longispina-group sensu lato in fact incorporates Hyalodaphnia species (Colbourne et al. 2006; Petrusek 2007).

The subgenus Ctenodaphnia needs a taxonomic revision (Petrusek et al. 2009; Petrusek et al. 2011). The Ctenodaphnia is a dominant subgenus in the southern hemisphere (showing bipolar distribution, sub-symmetric between the hemispheres), preferring small temporary waters, while Daphnia is a dominant subgenus in the northern hemisphere (showing antipolar distribution, dissymmetric between the hemispheres), preferring large lakes, but there are a few exceptions to this general rule (Kotov and